1. Field of the Invention
The present invention relates to a deaerating apparatus for deaerating a resist solution coated on for example a liquid crystal display (LCD) device and a treatment apparatus therewith.
2. Description of the Related Art
Generally, when an LCD substrate is fabricated, a circuit pattern is formed by photolithography technology. In the fabrication process, a resist solution is coated on the LCD substrate. The resist is exposed corresponding to the circuit pattern. Thereafter, the circuit pattern is developed.
In the coating and developing processes, as treatment solutions, along with a resist solution, developing solutions and resist solvents such as thinner are used. These treatment solutions contain gas due to various causes. When such treatment solutions contain gases, the following problems take place.
If the resist solution contains a gas, when the resist solution is coated, the gas becomes foam that prevents the resist solution from being equally coated. On the other hand, if the developing solution contain a gas, when a treatment substrate is filled with the developing solution, foam takes place, resulting in a non-developed portion. If a solvent such as thinner contains a gas, pores take place in the resist film.
To solve such problems, the treatment solutions are deaerated.
As an example of a liquid deaerating method, a liquid is poured into a pressure reducing tank. With a vacuum pump or the like, the liquid is vacuum-deaerated. As another deaerating method for a developing solution, as disclosed in Japanese Patent Laid-Open Application No. 9-7936, a liquid is flowed in a fluororesin tube. The liquid is vacuum-aerated from the outside of the resin tube. With pin holes, only a gas is removed from the liquid that is flowed in the tube.
However, when the liquid is vacuum-deaerated with the pressure reducing tank, although the surface portion of the liquid is sufficiently deaerated, the inner portion thereof is not sufficiently deaerated. Thus, the deaerating capability is insufficient.
On the other hand, when a liquid is deaerated with a fluororesin tube, the thickness of the tube cannot be reduced due to the restriction of the strength thereof. Thus, the permeability is low. Consequently, the deaerating capability is not sufficient. In particular, in the coating and developing processes for a LCD substrate that require a large amount of treatment solution, to supply a proper amount of deaerated treatment solution, the scale of the deaerating facility becomes large.